caphook

I have a 99 RX300 with 90,000 miles and in good shape. Have replaced all the O2 sensors MAF, plugs and timing belt.

one freeway engine light came on and then in about 5 minutes the temp gage went to zero and back up to normal about every 30 seconds. Continued to drive to the airport and will be gone for some time.

Would appreciate help on this. Will it hurt anything to drive it home (45 miles on toll road)? I suspect the engine coolant sensor but could be loose connection etc. according to you guys.

Where exactly is the temp sensor? pictures would be great or ref to a thread would really help.

Thanks. Caphook

salimshah

With engine cold, open radiator cap and check for coolant level. To get bye, you can add water [remember to get the proper antifreeze before winter].

For proper operation the sensor must be immersed in the coolant in the engine block.

As long as you have enough coolant having erratic indication is just a nuisance.
Assuming your engine is not overheating.

Salim

caphook

Thanks. It did not overheat but I will check it when I get back to the airport.

The thing I did not mention was that when the gague went to zero the A/C stopped cooling even though the blower still ran. Is the engine temp tied into the computer and the A/C? This seemed very strange and i have never seem this before except I know one of my old Chevys A/C cut out when the engine was under a heavy load to help it accelerate.

any advice appreciated. I did check the cost of a new sensor.

Caphook

salimshah

The ecu does take into consideration the engine temperature and I am assuming it takes the coolant temp sensor as an input.

Anything can happen, but most likely it is a loose wire or low coolant level [low enough that the sensor is no longer immersed in it].

Some one with camera can show you where the sensor is located.

Salim.

caphook

Thanks again. I hope some one with pictures shows up.

Lexmex

https://www.clublexus.com/forums/2889437-post3.html

caphook

My thanks to all who responded to my recent RX 300 Temp gauge issue with advice and particularly to Lexmex who sent pictures. I have used your (Lexmex) posts many times and thank you for the great advice.

After sitting at the airport for 3 weeks I returned with some spare water, just in case it was a coolant leak and found the battery was completely dead.

Got a jump and drove 45 miles home with no incident. Temp indicator worked perfectly and the CEL was off (off course since the battery was really dead). Battery should have been fully charged when I got home.

This morning battery would not start the car and the clock indicated a bad battery by resetting.

Final solution – bad battery. All seems fine now.

Reporting this since I have never had a bad battery cause this kind of problem. Have had three other battery failures in the vehicle and none like this.

I will be post more if symptoms reoccur.

Caphook

hypervish

In newer cars, the battery can have an effect on almost anything. They have so many electronics.